1. Field of the Invention
The present invention relates to the field of gas delivery systems, and more specifically to the mechanism of attachment and reconfiguration of a plurality of blocks which provide the gas routing conduits and passages for a gas panel.
2. Discussion of Related Art
Gas panels are used to control the flow of gases and gas mixtures in many manufacturing processes and machinery. A typical gas panel, such as gas panel 100 shown in FIG. 1, is made up of literally hundreds of discreet or individual components, such as valves 102, filters 104, flow regulators 106, pressure regulators 107, pressure transducers 109, and connections 108, connected together by tens (or hundreds) of feet of tubing 110. Gas panels are designed to provide desired functions, such as mixing and purging, by uniquely configuring the various discreet components.
A problem with present gas panels is that most of them are uniquely designed and configured to meet specific needs. Today there is simply no standard design in which gas panels are configured. Today it takes weeks to months to design a gas panel, fabricate all subassemblies, and then assemble the final product. Uniquely designing or configuring each new gas panel costs time and money. Additionally, the lack of a standard design makes it difficult for facilities' personnel to maintain, repair, and retrofit all the differently designed gas panels which may exist in a single facility. The unique designs require an intensive manual effort which results in a high cost to the customer for customized gas panels. Customized gas panels also make spare parts inventory management cumbersome and expensive.
Another problem with present gas panels is a large number of fittings 108 and welds required to interconnect all of the functional components. When tubes are welded to fittings 108, the heat generated during the welding process physically and chemically degrades the electropolish of the portion of the tube near the weld (i.e., the heat affected zone). The degraded finish of the heat affected zone can then be a substantial source of contaminant generation. Additionally, during the welding process metal vapor, such as manganese, can condense in the cooler portions of the tube and form deposits therein. Also, if elements being welded have different material composition (e.g., stainless steel with inconel), desired weld geometry and chemical properties are difficult to achieve. Thus, gas panels with large numbers of fittings and welds are incompatible with ultra clean gas systems which require extremely low levels of contaminants and particles. Additionally, high purity fittings 108 are expensive and can be difficult to obtain, thereby increasing the cost of any gas panel incorporating them.
Yet another problem associated with present gas panel designs is the large amount of tubing 110 used to route gas throughout the gas panel. Large volumes of tubing require large volumes of gas to fill the system and make it difficult to stabilize and control gas flows. Additionally, gas panels with excessive tubing require significant amounts of time to purge and isolate which can result in expensive downtime of essential manufacturing equipment, resulting in an increase in the cost of ownership. Still further, the more tubing a gas panel has, the more "wetted surface area" it has, which increases its likelihood of being a source of contamination in a manufacturing process.
U.S. patent application Ser. No. 08/760,150 filed on Dec. 3, 1996 has addressed the above issues by disclosing, as shown in FIGS. 2 and 3, modular building blocks for an integrated gas panel. The use of such building blocks greatly simplify the design and reduce the technical shortcomings associated with current gas panel technology. This invention relates to the mechanism employed for mounting the modular blocks. It is possible to mount the modular building blocks by individually drilling and tapping mounting holes in a customized pattern into a planar base fixture. Such a customized mounting plate will anchor the modular blocks with sufficient accuracy such that the low tolerance requirements of the block to block misalignment (+/-0.003") are met. However, customized drilling is both expensive and time consuming. Furthermore, easy reconfiguration of an existing gas panel is impossible if the reconfigured gas panel design has a different mounting hole footprint than the previous gas panel design. A breadboard-like mounting plate with pre-drilled and tapped mounting holes located at periodic locations on the mounting plate is also possible. Such a mounting plate eliminates the wasted time and money devoted to a customized mounting plate. However, a breadboard like design limits the total number of possible configurations on a mounting plate. That is, the modular blocks are not capable of being anchored at any of a continuous range of positions, but rather, their positions are limited to the relatively few discrete locations that are determined by the placement of the pre-drilled holes. Furthermore, a breadboard-like mounting plate forces the dimensions of the modular blocks to conform to the dimensions of the periodical spacing of the pre-drilled holes. This results in wasted space and possibly incompatible downstream product offerings. Additionally it is highly desirable to have a mounting technology that allows for the reconfiguration of gas panel even if the gas panel is fixed in a vertical position (for example on a wall). Such a capability would not even require that the gas panel be taken down in order to be reconfigured.
Thus, what is desired is a versatile mounting technology for a modular gas system that: 1) is easy to manufacture; 2) allows for rapid configuration or reconfiguration of a gas panel; 3) maximizes the available positions where modular blocks may be mounted; 4) allows for highly precise anchoring of modular blocks and 5) allows for reconfiguration even if the mounting fixture remains fixed in a vertical position.